1. Field of the Invention
The invention relates to a system and a method for determining the position of a sound source in relation to a reference position. The invention relates especially to a method for determining the individual positions of a plurality of sound sources of a multi channel audio system.
2. Related Art
Recently, multi channel audio and video systems have become more and more popular, especially for home entertainment application. In these systems, the sound is stored on a storage medium such as a DVD or a SACD (super audio CD) and the sound is encoded in bit streams for each channel of the multi channel audio system. Normally, home entertainment audio or video systems comprise five loudspeakers and one subwoofer. To optimize the sound produced from this loudspeaker system, the loudspeakers should have a special geometrical arrangement relative to each other. In the case of a 5.1 surround setup comprising five loudspeakers there exist standards (e.g. ITU-R BS 775-1 for 5.1 systems). In these standards, the position of the loudspeakers relative to an optimal listening position, generally known as a “sweet-spot” is defined. By way of example, in a 5.1 surround setup the five loudspeakers should have the following position in an horizontal plane: One loudspeaker in the center at 0° azimuth in the horizontal plane, one front left loudspeaker at 30°, one front right loudspeaker at −30°, one left surround loudspeaker at 110° and one right surround loudspeaker at −110°. This speaker setup will be explained in detail below. If these loudspeaker positions can be obtained, the surround sound may be optimized for the manner in which the sound was recorded and the manner in which the different channels of the multi channel audio system were encoded.
Especially in home cinema applications, but also in professional applications within a professional sound studio, it is not always possible to place the different loudspeakers at their ideal position. Furthermore, all loudspeakers should have the same distance relative to the listening position. This condition can also be difficult to fulfill, especially in the case where the loudspeakers have to be placed in a living room of an individual user of the system.
Available systems nowadays often comprise possibilities for adjusting the system to the room in which it is arranged. Therefore, the user of the system has to measure manually the distance of the different loudspeakers to the sweet-spot, determine the sound level of each loudspeaker at the sweet-spot and determine the lateral position of deviation of the different loudspeakers. Determining the angle of the loudspeaker relative to the center axis may be especially difficult.
Therefore, a need exists to automatically determine the position of a sound source such as a loudspeaker relative to a reference position.